Drying apparatus.



No. 747,788. I A PATENTED DEG. 22, `1903.

J. J. SMITH.

DRYING APPARATUS.

APPLICATION FILED NOV. 8, 1902.

No MODEL. N ks fa M UNITED .STATES Patented December 22, 1903.

PATENT OFFICE.

JOHNI J. SMITII, OF BOSTON, MASSACHUSETTS, ASSIGNOR'TO THE AMERICANCONDENSINGr DRIER COMPANY, or KITTERY, MAINE, A CORPORATION.

Duw/ING APPARATUS.

sPECIFICATION forming part of Letters Patent/No. 747,788, dated December22, 1903.

Application flied November s. 1902. serial 110.130,491. (No man.)

.To @ZZ whom it may concern:

Be it known that I, JOHN J. SMITH, a citizen of the United States, and aresident of Boston, county of Suffolk, State of Massachusetts,haveinvented an Improvementin DryingApparatus, of which the followingdescription, in connection with the accompanying drawings, is aspecificatiomlike letters on the drawings representing like parts. to,In the preservation of vegetable and animal m atter-s uch as foodproducts, tobacc0,&c.- evaporation has been heretofore employed invan-ions forms of apparatus to expel the moisture from'the materialheated; but one of the I5 great objections thereto is'the practicalelimination of the distinctive taste of the article treat-ed. This islargely due to the fact that lthe degree of heat employed and the steadyapplication of heat so expands the contained zo moisture of the materialtreated that the moisture-cells are burst or crushed, and while themoisture is undoubtedly extracted the essential oils or essences, whichlgive the characterist ic tasteA or flavor to an article,vare alsoeliminated. Y

In my present invention', which in the embodiment herein shown isparticularly adapted for drying tobacco or othei` leaf-like ma` terial,theextraction of the moisture is eiect- 3o ed without changing the cellformation of the material treated. So long as the material is thenmaintained free'from moistureitcan be kept indefinitely, and whengpermitted to take vup moisture it returns to its original condition,inasmuch as its cell structure has been unharmed and none of itsessential oils or essences extracted. Y l

The apparatus is also,'with slight changes ilrgmanipulation, welladapted for the treato ment ot' small fruits-such ascurrants, berrit-s,l&c.-potatoes,onions, spinach, eggs, arnljyarious lsh and animal foodproducts.

Jln vthe present embodiment of myinvention an endless foramiuous orperforated travel# ingcarrierorapron is mounted within aclosed lelongated chamber, and astiong current of dry air is heated by beingpassed overheating pipes or coils in close proximityto the carrier andthen is directedupon and drawn through 56. thelniaterial, the latterbeing fed onto theup` perrunofthecarrieratoneendofthechamber. As the airtraverses the material the warmer and cooler portions of the aircommingle therein and absorb the moisture contained in the material, andthe mo|sture-laden air is immediately drawn away and brought intocontact with condensing means, the moisture in the air being therebycondensed and dripping intoa suitable receptacle. The dried air then isreheated in'close proximity to the material 6o and again brought intocontact with the material ou the carrier, this process continuing as thematerial traverses' the chamber, so that gradually it is divested ofitsmoisture and left perfectly dry. '65 In my studies and experimentsrelating to the drying of o'rganic material I have found that thedestruction of thel cell structure ap. pears to be due to a continued orsteady application of heated air thereto, so that a steady 7o current ofheated air, even if continually drawn o'l as it `gathers or absordsmoisture, will expand the moisture in the cells land burst or disruptthe latter. This result Ibelieve to be due to the. fact that the' expan-75 sion of the contained moisture is elected at such -a rate that thecellular structure caunot adapt itself thereto at the same rate, andhence hecom es ruptured, so that the material will not retain itsoriginal taste and color. 8J Ihave also discovered that if such materialbe subjected to intermitting action of lheated air-that is, by warming:up and expanding the contained moisture, rotar-ding the expanu sion,then expanding again, and so on-the'85 moistur'e will be finallyeliminated without rupture of the cells, this action appearing to allowvthe cellular structure to gradually accommodate itself to the expansionof, the` lnoisturetherein. This may be likened in '9o Some degree to theaction of'a rapid pul of air directed into a soap-bubble or a thin ruh-`Y ber balloon, which instantly ruptures*` the sphere, whereas if t heair be introduced slowly, giving time for lhejlilm or the rubber tostretch, the sphere maybe expanded to large diameter and extremethinness. f f .Y Inapplying mydiscoveries to practicaluse I have foundthat the alternating expansion and retarding or arresting of theexpansion` loo cany in its eect be produced by subjecting cellularmaterial to the action of air which is not of one uniformtemperaturethat is to say, if the air be heated by passing it rapidlybetween steam pipes or coils arranged in close proximity to the materialsuch portions of the air as pass in immediate contact with the pipingwill be heated sufticiently to induce expansion of the moisturecontained in the cells; but the portions of the air not contacting with'the piping will be cooler. These cooler portions when impinging upon thematerial act to arrest the expansion set up by the warmer portions, andwhen this action is continued for a sufcient period, the moistnre-ladenair being withdrawn, the material will be dried with its cell structureintact. The moisture-laden air withdrawn from the material will be ot`practically uniform temperatu re, the portions of the air of higher andlower temperatures commingling within the material. Owing to the lowdegree of heat necessary' and the rapidity of the process, neitherfermentation nor rupture of the cell structure can take place.

Y The various novel features of my invention will be fully described inthe subjoined specification and particularly pointed out in thefollowing claims.

Figure l is a longitudinal sectional view of one form of apparatus forpracticing my inven tion. Fig. 2 is an enlarged transverse section onthe line 2 2Fig. 1, looking toward the right. Fig. 3 is a similar Viewon the line 3 3, Fig. 1; and Fig. 4 is also a transverse section on theline 4 4, Fig. 1, looking toward the right.

AReferring first to Fig. l, an elongated and substantially closedchamber A AW, substantially rectangular in cross-section, as mounted insuitable bearings near its ends transverse shafts B B', on which aresecured drums D D', respectively, and an endlessforaminous orreticulated carrier or apron DX is mounted upon the drums.

It will be seen by reference to Fig. 1 that the part AX of the chamberis' formed with a jog or longitudinal extension A, in which drum D islocated, the cover-plate ct of said extension being extended nearly tothe sur face of the carrier, and a clearance ax is left above 'the upperrun of the carrier or apron to admit the material to be treated, saidma` terial `being fed across the plate a onto the carrier. At itsopposite or discharge end the part A2X of the chamber is provided with ahood a', which extends overa portion ofthe periphery of the drum D', theopening a2 at the lower end of the hood permitting the discharge of thematerial into asuitaole receptacle R.

In the present embodiment of my invention the chamber is provided with atransverse partition a3, which may be about one-third of its length fromthe discharge end, said partition extending downward from the top of thechamber to near its bottom, with a splitlike opening ct4 for the upperrun of the carrier, the lower run traveling below said` partition. Asecond and similar partition a5, having an opening a6 for the upper run,is located near the drum D', as clearly shown in Fig. 1, and atransverse baftle-wall n.7 crosses the part A2X of the chamber betweenthe partitions and between the upper and lower runs of the carrier. Fromthe partition a? to the end wall of the extension A a longitudinal wallas extends, the top of said wall rising slightly above the upper run ofthe carrier in the main portion of the chamber AX. By reference to Figs.2 and 3 it will be seen that said 'wall divides the main chamber Ax intotwo parallel elongated compartments in communication at top and bottomof the wall, the

carrier moving in the larger compartment, and in order to support theupper run of the carrier guideledges l0 12 are secured to the wall asand the oppositie side'wall of chamber AX, respectively, the carrierbeing as wide substantially as the larger elongated compartment. Similarledges 120 are provided in the part A of the chamber, such part beingnarrower than the main part (see Fig. 4) and extending from thepartition 03 to the discharge end,'the lower run of the carriertraveling over rollers m75, adjacent the bottom of the closed chamber.

The drum D `is rotated in any suitable manner by mechanism (not shown)and at such a speed as willcause the carrier to travel at a slow ratethrough the closed chamber, the material fed onto the upper run of thecarrier at the feed end (shown at the left,

Fig.'1) being thus moved slowly and uniformly through the chamber to thehead a' and discharged through the opening a2.

To clean the carrier and prevent any of the material sticking thereto, Ihave shown in Figa'l a revolving brush 25, driven in any suitableymanner and adapted tonot only clean the carrier, `but to throw or directthe dried product into the receptacle R'. This receptacle or bin may beprovided with anyl well-known or suitable pressing device to press thedried material in'to compact form 4suitable for packing ahd storage ortransportation; but inasmuch as the compressing niechanislnfor the driedmaterial forms no part of this inventionl have not illustrated the sameherein.

In the smaller of thetwo elongated compartments in the main chamber AX,I have placed condensing means, shown as a series of coils of piping C,through which any snitable cooling or refrigerating medium is passed toreduce the temperature of the condenser to the desired point, therefrigerating duid entering the coil at c, Fig. 2,v and controlled by asuitable valve c', and after circulating through the various bends ofthe coils it may be withdrawn through the pipe c2, Fig. 3, having asuitable controlling-valve c3.

In the larger long compartment I .arrangel IOO IIO

quite near thereto, and these' coils may extend a little more thanhalfthe length of the compartment, While the coils H' are placed abovethe upper run of the carrier and ex tend substantially to the partition@sand are also in close proximity to the carrier.

.Cross-girths g, secured at their ends tothe longitudinal Wall asand theopposite side wall of the main chamber A and at the lower part thereof,are provided with bearings g for the axes of suitable fans F F', eachfan-axis having a beveled gearj'tbereon in mesh with a similar gear j",fast on a transverse shaft f2, extended through the side wall of themain chamber and provided with a beltor otherpulleyf3,so that theseveral shafts may be driven by means of a belt traversing the same eX-terior to the chamber AX. The fans F are located below the heating-coilsH and are so constructed that theydirect the blast or current upwardrapidly against and through such heating-coils, while the fans F' arearranged as suction-fans or to produce a downdraft. The particular formof the fans isfimmaterial, however,provided the'draft or current israpid and upward along so much of the upper run of the carrier as isover the heatingcoil H and downward along so much of the carrier-run asis below the heating-coils H.

The heating-coils are traversed by any suitable heating medium,preferably steam, and

governed by a suitable valve h, Fig. 3,a sufficient degree of heat beingprovided to grad ually and gently expel the moisture from the materialupon the carrier. This material is passed over the heating-coil H, andthe upward current of air caused by the fans F is heated by contact withthe heating-coils H and passes through the upper run of the carrierandthe material thereon, which is relatively heavy, largely by reason ofits contained moisture, the portions of air contacting with the coilsbeing higher in temperature than the portions of air further removedtherefrom. These Warmer and cooler portions or currents impiuge upon andare arrested by the material on the carrier. The warmer portions act toexpand the contained moisture, and thereby stretch the cellularstructure of the material, while the cooler portions of the air arrestsuch expansion and stretching, giving the cell structure an opportunityto accommodate itself to thechanging internal conditions. The portionsor currents of air commiugle within the material y and passtherethrough, extracting or carrying along a certain portion of themoisture therefrom, and the moisture-,laden heated air then comes incontact with the refrigerating or condensing Ameans C, and the con--tain'ed moisture is immediately condensed -and drips from the coils Cinto a suitable drip pan or trough CX.

The air which is thus dried and cooled falls toward the bottom of theclosed chamber and Vis drawn from underneath the wall as by suction ofthe fans F and is again driven through the heater and up through thematerial on the carrier to re. peat the former process, the direction ofthe circulating currents of air being shown quite clearly by the'arrowsin Fig. 2. p

It is to be understood that the constant changes in the internalstructure of the material due to the action of theportions of the air ofdifferent temperatures are instantaneous, the expansive action and itsarrest following each other ina sequence too rapid to be measured.'

When .the travel of the carrier brings the material below the heater H',such material has been divestedot' a large proportion of its moisture,and henceismuchlighterin weight, and should the air-current be directedupwardly upon theV material it would tend to cause it to y about thechamber. To prevent this, the suction-fans F are employed, and they actto draw the air from the top of the chamber down through the heaterH andthrough the material on the carrier, so that this air, which-.takes upthe remaining moisture in the material in the manner described, isdirected to the bottom of the chamber and vbeneath the bottom of thelongitudinal wallaB to the condensing means to be cooled there-4 by andto have its moisture removed by condensation.

The suction induced by the fans F acts to draw the air up through thecondenser in this part of the chamber, and this cooled and dry air isagain heated by contact with the heater 'H' before it again comes incontact with the could then be immediately discharged and in conditionfor packing.

The apparatus herein shown is particularly adapted for treating tobacco,and should the leavesthereof be packed at once as they pass through thepartition a3 they would be iu such a brittle condition that they wouldbreak into small pieces, and it is therefore necessary to restore -asufficient amount of moisture to the material to render it pliableenough to retain its shape and character without breaking when packed.To this end I have arranged the partA2 as an ordering compartment orsection to soften the previously-dried product preparatory. to packingor baling. Between the partitions a3 and a7 an updraft-fan F2 is'locatedand driven in suitable manner todirect an air-current up through theupper run. of the carrier and the material thereon, and above thisportion of the ordering compartment or section 1 have placedasprayiug-'coil M, having tine perforations on its under part, as at mx,Fig. 4f, to direct .steam-jets, or it may be water or other ICO IIO

liquid in a finely-divided condition or spray,

upon the 'material as it passesbeneath the coil M.

The amount of .moisture directed upon the material is regulated by meansof a valve m2,

. Fig. 4, and the upward current of air caused the transverse slot oraperture a6 in the par- 4tit'ion-wall a5 and be discharged from theopening a2 of the hood. This final downdraft serves'to collect thematerial again in a layer more or less compact upon the carrierLso thatyit will be evenly and readily discharged.

The apparatus herein shown is exceedingly ecient and requires a smallamountof power to operate it, as there is little or no back pressure tocontend with, the 'small' amount of outside air which is admittedthrough the enl trance-opening ax merely serving to take the place'ofsuch air as is discharged through the openings2 at the discharge end ofthe chamber. There is a constant and continuous changing of the air inthe main chamber AX from dry andV heated air to warm moisture-r ladenair, and this is immed iatelytransform'ed bythe 'condensingorrefrigerating means to dry an`d cool air, ready to be again delivered ina hot or Warm andA dry state upon the material beingdried. The heat isnotv raised to such a degree asl would canse such rapid evaporation" ofthe contained moisture as would tend to break or fracture the c ellstrucvessarytio shut-olf the spraying device M and 6o ture'of'thematerial being treated, as it is obvious that even with the apparatusherein shown the heat could be made of sufliciently high temperature toeffect such an undesir-l able result, and the passage of the materialthrough theapparatu's is sufficiently rapid to preventany fermentationfrombeing set up.

lHerein the fans F are rotated in one'direction'V to provide an updraftfor-the air-current, an'd the fans -F' are rotated in the oppositedirection to provide a downdraft.

In Figurlthe fan F2 is supposed to berotated in the same direction asthe fans F', and the faul?s is oppositelyrotated. I

If it is desired to'treat other material by the apparatus hereinshownand to Ideliver it in a completely-dried condition, it is only nectostop the rotation of the fan F2, as will be manifest from an inspectionof the drawings 4 Qand the foregoing description.

My invention is not restricted to the-pre- 'cise construction andarrangementherein shown, as the same m'ay be modified` or rearranged invarousparticulars without de- .an elongated'closed chamber, an endless,

partingfrom -the spirit and scope of my intraveling, foraminous carriertherein to susr tain upon its upper run the material to be treated, aheating-coil in close proximity to the said carrier, means to direct arapid current of dry air through the coil and upon and through thematerial, to expel and take up moisture therefrom, and means tocontinuously condense the moisture and cool the air after it'has acteduponthe material, the dry cold air being again heated and directed uponthe material.

2. In an apparatus of the class described, an elongated closed chamber,having a hot and a cold compartment, extended side by side andlcommunicating at top and bottom throughout its. length, means to conveythe material along the hot compartment near its top, means to induce/arapid transverse circulation of airin the chamber, whereby the air ladenwith moisture from the material heated will be cooled and dried Vin thecold compartment, and pass therefrom in such condition to the hotcompartment, and heating-coils in the latter in closeproximity to theconveying means for'thematerial, to act upon the dried and cooled air asit is directed upon the material. t

3. In an apparatus of theclass described, a closed, elongated chamber,an endless traveling carrier therein to support on its upper run thematerial to be treated, and means to alternately heat and cool acontinuous current of air directed upon the material, thelair when hotacting upon thev material to take up moisture therefrom, yand whencooled causing condensation of the contained moistu re, the heatingmeans being located in close proximity tothe carrier to cause 'uon-u,niformly-heated air to impinge'upon the material thereon. I

. 4. In aneapparatus of the class' described, an elongated, closedchamber, having allot and a cold compartment, extended VVside by sideand in continuous communication at top and bottomthroughoutits length,means to convey the material along. the' hot compartment near its top,aheating-coil located in `close proximity to the conveying means,acondenser in the cold'compartment,and'means 'to rapidly force airthrough the heatinfggc'oil IOO and' thence directly upon and throughthmI material to be treated and thence to the cold chamber, the air beingcooled auddricd therein by the condenser, the driedand cooled airreturning thence to-the hot compartment' to be again driuenthrough theheatingfcoil upon y the material.

'5, In an apparatus of vthe classdescribed, an elongated, 'closedchamber,-.an endless,

traveling, foraminous carrier therein to sustain upon its upper run thematerial to be treated, a heater in close proximity to and extendinglongitudinally of the upper run of the carrier, a condensing-compartmentcommunicating at top and bottom with the main portion of the chamber,and a fan in thelatter, the fan effecting circulation of cold, dry airfrom the condensingcompartment into the main chamber and v driving itrapidly through theheater, to impinge directly upon the material on thecarrier and to pass therefrom to the condensing-compartment.

l6. In an apparatus of the class described, an elongated, closed chamberhaving hot and cold compartments communicating at top and bottomthroughout the length of said chamber, an endless, foraminous, travelingcarrier in the hot compartment, to receive at one end material to betreated and to discharge it atthe other end, means to direct abcurrent4of heated, dry air up through ythe material near the feed end of thechamber, means to direct a current of heated and dry air down upon thematerial as it approaches the discharge end of the chamber, the airas itpasses through and in contact with the material extracting the-moisturetherefrom and passing thence to the cold compartment, 'and refrig'erating means' in the latter to cool the 'air and condense the moisturecarried thereby.

7. In apparatus of the class described, a closed chamber, vmeansto'continuously move vmaterial to be treated from one to the other endof the chamber, means to cause a current of air to .circulatecontinuously through the chamber to act upon the material to he treated,and means to rapidly and non-uniformly heat, andto cool and dry suchcurrent of air, the heating means beinglocated in close proximity to thematerial whereby the material is subjected to the act-ion of dryportions of warmer and cooler air, to extract its moisture whilepreserving intact the cell structure of the material.

In testimony whereof I have signed.v my name to this specification inthe presence of two subscribing witnesses.

JOHN J. SMITH. Witnesses: v y

JoHN C, EDWARDS, MARGARET A. DUNN.

